The present invention relates to a plasma processing apparatus such as a plasma vapor-phase growth apparatus for forming thin film by a plasma (CVD) (Chemical Vapor Deposition) method, a dry etching apparatus for using a low-temperature plasma to perform an etching operation on the surfaces of an object, and the like.
The plasma processing for thin-film forming by the plasma CVD method or for dry-etching using the low-temperature plasma is indispensable in the semiconductor process in recent years.
In these plasma processes, there is a technical problem to quicken the processing speed (in the plasma CVD, the accumulation speed, in the dry etching, the etching speed). In order to realize the high speed, it is required to increase the density of the high-frequency power which is adapted to generate the plasma.
However, increasing of the high-frequency power density is likely to cause sparks on the surfaces on the high-frequency electrode, with the result that the following problems are caused.
(1) In the case of the plasma CVD:
(a) Particles adhere on the object for accumulating the vapor-phase thin to easily cause the film defect. PA1 (b) As the gas feed condition or the plasma condition for accumulating the CVD changes unstably, dispersion is caused in the film thickness and the film quality so as to deteriorate reproducibility. PA1 (c) High-frequency noises are caused, thus reducing the reliability of the plasma CVD apparatus itself. PA1 (a) As the plasma condition becomes unequal, the uniformity of etching is likely to be deteriorated or the resist damages are likely to be caused. PA1 (b) The high-frequency noises are caused, thus reducing the reliability of the plasma CVD apparatus itself.
(2) In the case of the dry etching (i.e., plasma etching):
Because of the above-described reasons, to realize the high speed of the plasma processing, it is an important task to prevent the sparks from occurring in the high-frequency electrode, which applies the high-frequency power for generating the plasma.